This disclosure is generally related to high speed wireless networks and devices. In particular, this disclosure is related to configuration of a maximum retransmission number for an automatic repeat request (ARQ) scheme, e.g., hybrid ARQ (HARQ), implemented in wireless networks, e.g., third generation (“3G”) or fourth generation (“4G”) networks. Examples of 3G networks include networks operating on wireless technologies such as Code Division Multiple Access (CDMA) and Evolution-Data Optimized or Evolution-Data only (“EvDO”)/CDMA. Examples of 4G networks include networks operating on wireless technologies include Worldwide Interoperability for Microwave Access (“WiMAX”) technologies and Long Term Evolution (LTE) technologies.
Manual selective implementation of a well-known error control technique for data transmission, Automatic repeat-request (ARQ), utilizes acknowledgments and timeouts to achieve reliable data transmission. ARQ acknowledgments are messages sent by the receiver to the transmitter to indicate that the receiver correctly received an information unit. Timeouts are reasonable points in time after the sender transmits the information unit. The sender usually re-transmits the information unit if it does not receive an acknowledgment before the timeout. It continues to re-transmit the information unit until it either receives an acknowledgment from the receiver or exceeds a predefined number of re-transmission attempts. Conventional types of ARQ protocols include “stop-and-wait ARQ”, “go-back-N ARQ” and “selective repeat ARQ”. These protocols typically reside in the Data Link or Transport Layer 2 of the OSI 7-layer model.
Conventional Hybrid ARQ (HARQ) is a commonly used extension of the ARQ error control method that exhibits better performance, particularly over wireless channels. HARQ is used in several conventional wireless communications systems including High-Speed Downlink Packet Access (HSDPA) and High-Speed Uplink Packet Access (HSUPA) (i.e., third generation mobile telephony communications protocols in the High-Speed Packet Access (HSPA) family) which allow networks based on Universal Mobile Telecommunications System (UMTS) to have higher data transfer speeds and capacity on downlink and uplink, respectively, for mobile phone networks using the UMTS.
HARQ has also been used in the IEEE 802.16-2009 standard for WiMAX, and in LTE standard. Presently, HARQ provides an important technology for increasing data transmission reliability and data throughput in mobile communication systems. Specifically, in the WiMAX implementation, HARQ refers to a combination of ARQ and PHY layer reception techniques like Forward Error Correction (FEC) and signal combining techniques. Different from ARQ operating solely at the MAC layer, HARQ allows the receiver to perform soft-combining of retransmitted packets and therefore may provide some measure of improvement in spectral efficiency.
In current standards, e.g., in IEEE 802.16-2009 standard, the value for maximum number of retransmissions for HARQ is the same for all service flows and media access control (MAC) management messages, and is set statically, i.e., not changed dynamically, e.g., during a communication session. However, service flows and MAC management messages may have different Quality of Service (QoS) requirements, e.g., in terms of different delay and packet loss requirements. For example, a Voice over IP (VoIP) application is typically delay-sensitive but loss-tolerant, while a TCP flow application is delay-tolerant but loss-sensitive, and MAC management messages are both delay-sensitive and loss-sensitive. Accordingly, assigning a same value to the maximum number of retransmissions for HARQ for all service flows and MAC management messages may not align well with different QoS requirements, and thus, the advantage of using the HARQ scheme may not be fully maximized.
What is therefore needed is a solution to differentiate a maximum number of retransmissions assigned for service flows and a maximum retransmission number assigned for MAC management messages. What is further needed is a solution to reconfigure the maximum number of retransmissions related to one or more service flows for a specific user, e.g., based on QoS requirements of those one or more service flows, current channel conditions experienced by the user, etc.